THEORY OF MAST REPRODUCTION IN PLANTS: STORAGE-SIZE DEPENDENT STRATEGY

The amount of available resource can be considered to restrict mast seeding behavior in plants, regardless of the cause of masting itself. The reproductive strategy of a plant that has stopped growing, but continues to maintain a constant size, is based on the allocation of assimilated resources between reproduction and storage. If both plant death and population growth rates are constant, the plant strategy is dependent only on its own storage size. Conditions for the evolution of mast reproduction were analyzed under both constant and varying environments, from the view point of storage-size dependent strategy, which is influenced by three parameters: the advantage coefficient of mast seeding, β; the cost coefficient of delayed seeding, γ; and the assimilation rate, P. The model indicated that: (1) mast seeding evolves only with a greater than linear increase in reproductive success with effort (β > 1) under both constant and varying environments; (2) in mast seeding, a critical storage size, S_c *, occurs, above which plants utilize all storage for reproduction; (3) in a constant environment, S_c * increases with increasing β and P and/or decreasing γ; (4) concomitant with (3), an intermasting period, τ, also increases with increasing β and decreasing 7, but is independent of P; (5) in a varying environment, S_c * and the average of τ increase with increasing variance of the assimilation rate, P; and (6) concomitant with (5), the intermasting period has a certain probability distribution. In addition, reproductive synchrony within the population and the relationship between mast seeding and species diversity are discussed.